I don't believe the development of the B-29 would be much different than other heavies already in game. Weapon's data is already there, flight model a is probably a standard fill-in-the-data template. Developing the 3D model, interiors, etc., would be the biggest hurdle.
Perking them makes sense, rear bases launches make sense...so to limit the Uber-ability of the plane, don't make it a formation bomber, make it a stand-alone single.
Does it perform, yes. Will Brewsters and Spit 16s catch them? Not if they're up in the statosphere. However, historically, B-29 accuracy was horrible at high altitude because of the environmental effects on the bombs as they fell. The higher you go, the less accurate the payload delivery. Lower altitude, you increase the chances of interception.
The Ta-152 was designed to be a high-altitude interceptor, its purpose was to kill bombers. 262s and 163s would have something worth climbing to alt to intercept. The uber-defensive abilities of the 29 are effectively countered by the speed of the 262 and 163, and the size of the 163 as a target, especially if its a single aircraft. A single B-29 would carry less than formation of Lancs, although it would be higher and faster.
I like the idea of a prototype '45 arena, even if on a limited basis. P-51H, XP-47H, XP-72, A7M Reppu, F2G Corsair, F7F Tigercat, F8F Bearcat, Meteor, P-80, P-40Q, MB.5, Supermarine Spiteful, etc. I do however, agree that more additions should be made to the existing plane and GV set before we start looking at what-if scenarios.
What it boils down to really - any aircraft can be added to the game. HTC has the ability to impose whatever limitations it wants to make the aircraft viable. Thinking that the '29 would alter the game so dramatically to influence gameplay is wrong - HTC has the ability to control all aspects of balance, from the micro to macro levels. Us relying on a 2 year old post from a staffer is also not much - requirements and demands and priorities change almost daily - not only from the stuff we don't see or hear about from within the company, but from who they're competing with in the market, player requests and demands, the implementation of new technologies, maintenance of the existing platform and future, heavy-duty changes that might be coming down the pike. While I would like to see strategic bombing improved in this game, the overwhelming majority of the players in this game operate under 10K.